Bimetallic rivet.



H S I F L U H 3 D BIMETALLIG RIVET.

APPLICATION FILED MAB..14,1907.

Patented Jan. 3, 1911.

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mines-s95.- %MMZ UNITED STATES PATENT OFFICF DAVID S. HULFISI-I, OF CHICAGO, ILLINOIS, ASSIGNOR T MCMEEN & MILLER, OF CHICAGO, ILLINOIS, A COPARTNERSHIP.

BIMETALLIC RIVET.

To all whom it may concern:

Be it known that I, :DAVID S. I-Iumusrr, a citizen of the United States, residing at Chicago, county of Cook, and State of Illinois, have invented a new and useful Improve ment in Bimetallic Rivets, of which the following is a specification.

My invention comprises a bimetallic rivet.

It has as its object the production of a cheap substitute for platinum rivets for electrical contact points In'the drawings, Figures 1, 2 and 3 show end, side and section of a cylindrical bimetallic rivet blank; Figs. 1 and, 5 show, processes of forming same, and Fig. 6 shows the finished product; Fig. 7 shows the finished product as applied to practice. Fig. 8 shows a more elaborate process of installing the bimetallic rivet for service as an electrical contact point, and Figs. 9 and 10 are finishing processes completing the process of installation begun by the process of Fig. 8.

Fig. 1 shows end view of a piececf bimetallic wire. Bimetallic wires are old in the art, being made and sold generally of copper core with tin surface, and of iron core with copper surface; the wire which I illustrate in Fig. 1 I prefer to have of platinum core with a surface of any baser metal, as copper or silver or tin, and preferably of a metal which maybe softened very much by annealing. Bimetallic wires usually are made' by uniting a rod of one metal with a cylinder of another metal and then drawing the resulting composite cylinder into wire; however, my invention is independent of the means or method of manufacture of the bimetallic Wire. Such bimetallic Wire with platinum core being made, it is cut into lengths, as shown in Figs. 1, 2 and 3. The dimensions may be as desired, but for rivets for electrical contact points to be fixed in springs of relays and similar electrical switches, the dimensions may be conveniently .04 inch in diameter and .08 inch long, the platinum being probably .015 in diameter, showing a large economy in the quantity of platinum used as compared with a solid platinum rivet blank.

The first process of manufacture consists of producing a bimetallic Wire by some process, say that which is used in producing the detectors of Fessenden Wireless telegraph equipments, but of larger diameter; the next step is to cut the Wire into lengths, thus pro- Specification of Letters Patent.

Application'filed March 14, 1907.

Patented Jan. 3, 1911.

Serial No. 362,402.

ducing the blanks or billets shown in Figs. 1, 2 and 3; the next step is shown in Fig. 4, where 3 and 4 are forming dies which form the outer portion of the bimetallic blank down as a preliminary formation of a rivet head, the intention being to strip the baser metal from the platinum as much as possible; and Fig. 5 shows the last process where in the die 5 forms down the inner metal of the rivet, producing the round or pointed head as desired, the top or contact surface of the rivet head being composed entirely of platinum, or of the core of the rivet. Thus there is produced the completed article of manufacture illustrated in elevation in Fig. 6, although the rivet is practically complete for service in the form shown in Fig. 4.

In applying the article of Fig. 6.to service, it is passed through the support, as 6, which is to hold it, and riveted down, as shown in section in Fig. 7. If preferred, a die, as 7, may be used to swage the outer metal first, and the rivet may be left for service in the form of Fig. 8, or it may be finished by a cup die as in Fig. 9 or by a fiat die as in Fig. 10. Figs. 8, 9 and 10 show forms suitable for applying for service where the metal web 6 is required to be tipped for electrical contact on both sides.

I claim as my invention, the bimetallic rivet produced from bimetallic wire or otherwise to effect the same resulting article of manufacture; modifications of the process consist of forming the dross rivet and drilling for the platinum core, or of dissolving the dross away as in the Fessenden processes, if so desired.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

1. The process of making a bimetallic rivet which consists in stripping back the outer metal of a bimetallic wire and then heading down the inner metal, said Wire consisting of a cylindrical core surrounded by a concentric layer of different metal.

2. The process of making a bimetallic rivet which consists in stripping back the outer metal of a bimetallic wire comprising a cylindrical core and a concentric outer layer, and forming said outer metal to make an annular rib around the bimetallic Wire, and then heading down the inner metal upon the annulus thus formed.

8. The process of making a bimetallic rivet which consists of cutting; into blank billets a bimetallic Wire composed of a eylindrical core surrounded by a concentric layer of dilferent metal, removing the outer metal of the billet frOm the inner metal for :1 short distance at the end of thebillet to bare the inner metal, and then heading; down the inner metal.

in testimony wnereoI, i nave Slgl16u. 111 y name to this specification in the presence of 10 two subscribing- Witnesses.

DAVID S HULFISH.

Vitnesses HAZAEL C. PRADO, HARRIET L.- SMITH. 

